Implement CHA through type mask and TypedSelector in the simple type inferrer.

sdk/lib/_internal/compiler/implementation/ssa/builder.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of ssa;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 4092 matching lines @@
     List<HInstruction> inputs = <HInstruction>[];
     for (Link<Node> link = node.entries.nodes;
          !link.isEmpty;
          link = link.tail) {
       visit(link.head);
       inputs.add(pop());
       inputs.add(pop());
     }
     HLiteralList keyValuePairs = new HLiteralList(inputs);
     add(keyValuePairs);
-    DartType mapType = compiler.mapLiteralClass.computeType(compiler);
-    // TODO(ngeoffray): Use the actual implementation type of a map
-    // literal.
-    pushInvokeHelper1(backend.getMapMaker(), keyValuePairs,
-        new HType.nonNullSubtype(mapType, compiler));
+    HType mapType = new HType.nonNullSubtype(
+        backend.mapLiteralClass.computeType(compiler), compiler);
+    pushInvokeHelper1(backend.getMapMaker(), keyValuePairs, mapType);
   }
 
   visitLiteralMapEntry(LiteralMapEntry node) {
     visit(node.value);
     visit(node.key);
   }
 
   visitNamedArgument(NamedArgument node) {
     visit(node.expression);
   }
@@ skipping 970 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }